Caffeine has been a prohibited substance before, but it was removed in 2003 to prevent athletes "who . . . drink cola or coffee from testing positive to banned substances," Agence France-Presse reported at the time.

"Hence the thresholds or reporting values established for some prohibited substances naturally present in foodstuff," Durand said.

Without more research, WADA can't predict what its threshold might be. Nor does the agency want to predict whether it's likely caffeine will wind up back on the prohibited list at this point, but it appears, whatever happens, it's likely Diaw and others won't have to give up their pregame rituals.